Most Americans are willing to have their genetic information shared in a national database, but they first want to be asked, researchers report.

The new study included participants in the Adult Changes in Thought (ACT) study, a long-term project tracking age-related changes in thousands of patients that's being conducted by a team at the Group Health Research Institute and the University of Washington in Seattle.

When asked if their anonymous genetic and medical data could be shared in a national database, 86 percent of the ACT participants agreed. The researchers then surveyed 365 of the participants whose reason for agreeing to share their genetic data was mostly due to their "desire to help others."

Of those 365 people, 90 percent said it was important to have been asked for reconsent, which is additional informed consent that's given by research participants before their information is used for a purpose beyond what they agreed to originally.

"We were surprised that so many people felt it was important for us to ask them, even though they decided to give their consent. This indicates that even if most of a study's participants would agree to data sharing, it's still crucial to ask them," lead author Evette J. Ludman, a senior research associate at Group Health Research Institute, said in an institute news release.

The study is published in the September issue of the Journal of Empirical Research on Human Research Ethics.

"Trust is a two-way street, and human research requires lots of trust," Ludman said. "People have an understandable feeling of ownership over their bodies and medical records, including their genetic information. Researchers show we're worthy of trust when we ask research participants for permission to use their information in a way that they haven't already agreed to."